Over the years, various counterflow or cross-flow types of heat exchangers have been employed in any of a variety of heat exchange operations. One type of counterflow heat exchanger employs generally concentric tubes or pipes with one heat exchange fluid flowing in the inner tube in a given direction and the other heat exchange fluid flowing in a space between the inner tube and the inner wall of the outer tube and in the opposite direction. In some instances, these heat exchangers have been made of rigid pipe to have one or more passes with the passes being connected together by conventional pipe fittings.
In other instances, flexible tubing has been wound in a continuous length with fittings applied to their ends. In one such heat exchanger, inner copper tubes and outer steel tubes are formed together in one continuous piece without joints and the fittings applied to their ends.
While these constructions work well for their intended purposes, the use of rigid pipes with pipe fittings is labor intensive in terms of assembly while forming concentric tubes together in one continuous piece requires sophisticated equipment such that the product is expensive.
The present invention is directed to overcoming one or more of the above problems.